The general objective of the project is to gain a better understanding of the ecology and biology of WNV and other potentially relevant arbovirus in a tropical ecosystem (including dengue viruses and Venezuelan equine encephalitis virus). The knowledge gained will contribute to the development of locally appropriate arboviral-disease surveillance and control methods. Additionally, this effort offers the opportunity to detect novel arboviruses of public health significance. It will also strengthen the capacity within the UVG-CHS to conduct outbreak investigations of suspected arboviral etiology in Guatemala and neighboring countries of Central America, in assistance to the Ministries of Health in the region. 1. Confirm patterns of WNV temporal and spatial transmission in Puerto Barrios, Guatemala, and their possible relationships with environmental variables. 2. Confirmation of Culex species as important vectors of WNV and other arboviruses such as VEEV and Group C Bunya viruses. 3. Validate published taxonomic keys for culicines in Guatemala and develop simplified identification methods including molecular assays to improve the identification of Culex mosquitoes from Guatemala. 4. Verify the status of Quiscalus mexicanus as the principal avian WNV amplifying host and identify microhabitat factors that favor vector-host contact. 5. Identify arboviruses isolated from mosquitoes and other vertebrates and characterize their phylogenetic relationships and phenotype. 6. Asses infection rates in suspect vector mosquitoes, arboviral seroprevalence in domestic animals and suspect reservoir hosts, in communities where arboviral human disease is detected by IEIP (International Emerging Infections Program) clinical studies in Guatemala.